1. Field of the Invention
The present invention relates to a lighting control circuit for use in controlling lighting of a solid-state light-emitting element, a lamp, and a lighting control method using the lighting control circuit.
2. Description of the Related Art
A lamp using, for example, a light-emitting diode (LED) as a battery-friendly solid-state light-emitting element is proposed instead of a fluorescent lamp having filament electrodes (refer to, for example, JP2008-277188A).
According to the technique disclosed in JP2008-277188A, a lamp having a solid-state light-emitting element can be exchangeably attached not only to a lighting device for a glow starter fluorescent lamp or a rapid starter fluorescent lamp but also to a lighting device having an inverter electronic ballast for a fluorescent lamp.
However, in a case of attaching a lamp having a rectifier circuit, smoothing circuit, and solid-state light-emitting element to an electronic ballast of a fluorescent lamp, a lamp different from a commercial fluorescent lamp is connected to an electronic ballast of a fluorescent lamp, so that a protection operation of the electronic ballast operates, which may disturb the lighting of the lamp.
Unstable lighting of a lamp is a generally known fact. In order to avoid such unstable lighting of the lamp, the output voltage of the electric ballast is set to be a voltage (equal voltage) close to the output voltage while a fluorescent lamp is connected to the electric ballast when the lamp is connected to the electric ballast instead of the fluorescent lamp.
However, when the output voltage while the lamp is connected to the electric ballast is set to be close to the output voltage while the fluorescent lamp is connected to the electric ballast, the protection operation of the electric ballast becomes difficult to operate. Therefore, it is disadvantageous in electric power saving although it is advantageous in stable lighting of a lamp.
On the other hand, when the output voltage while the lamp is connected to the electric ballast is set to be lower than the output voltage while the fluorescent lamp is connected to the electric ballast, the electric power saving can be improved, but the lighting of the lamp becomes unstable.